1. Field of the Invention
The present invention relates to a system for removing loose debris from streets and other surfaces. Particularly, the present invention relates to snow or ice removal from regular and irregular surfaces. More particularly, the present invention relates to a system that can be configured to perform various ground cleaning operations. More particularly yet, the present invention relates to a snow removal system that fractures the snow covering a surface, lifts the fractured snow from the surface, and discharges it through an impeller/discharge system. Most particularly, the present invention uses a stiff but flexible stepped triple finger mechanism to fracture and lift the snow and deliver it to an impeller assembly that transfers the snow and laterally discharges it, at an adjustable height above the surface from which it is expelled.
2. Description of Prior Art
Although the utility of the present invention is not limited to snow removal, the relevant prior art lies in the field of snow removal mechanisms. Among the many different means for removing snow from ground surfaces snowplows are the best known. Nevertheless, snow removal by snowplow has a number of inherent disadvantages. A snowplow typically requires several passes to clear a roadway of snow. In the first pass, it clears a swath, discharging the snow to the side of the plow, thereby creating snowbanks that narrow the roadway and impair visibility for vehicle operators or pedestrians. In a subsequent pass or passes, the plow works at pushing the snowbank further away from the roadway. Furthermore, highway snowplows typically require a certain minimum forward speed if the plows are to impart to the snow the velocity needed for the snow to travel across the face of the plow. In congested traffic conditions in which the snowplow is prevented from maintaining this minimum speed, snow spillage may occur at the edge of the plow not intended to discharge snow, leaving ridges of snow in the middle of the roadway or causing the vehicle to stall. Also, snowplow blades are straight and rigid, designed to remove snow from regular surfaces. When they contact fixed protrusions from the surface, these blades may become bent or damaged in other ways, requiring costly repair or replacement. Also, the plow blade does not remove the snow from the ground cleanly, but rather, leaves surface recesses filled with snow.
Snowblowers have certain advantages over plows: they do not require a minimum forward velocity of the prime mover in order to move the snow and, depending on the orientation of the discharge outlet and the throw speed, they may avoid creating snowbanks at the roadside. Yet, there are also disadvantages inherent to snowblowers, existing in all of their many types. Snowblowers typically engage the snow by means of cutters, brushes, or augers, and transport the snow to a blower unit which discharges it to either side of the snowblower at some distance from the roadway. Cole (U.S. Pat. No. 2,103,514; 1937) teaches a system that uses a pair of rotary cutters to engage and then transport the snow or ice to a centrally located blower unit, which then discharges the snow or ice to either side of the vehicle as desired. Another system teaches the use of a rotary drum having blades located around its periphery to cut and lift snow and convey it to a discharge unit Maxfield et al. (U.S. Pat. No. 5,209,003; 1993). The rigidity of augers or cutters, as taught by the systems of Cole or Maxfield et al. creates several difficulties. For one thing, the leading edge of an auger or a rotary cutter is necessarily exposed to allow engagement with the snow; these rigid, churning augers or cutters make such snowblowers inherently dangerous to use. Furthermore, rigid augers and cutters can damagexe2x80x94or be damaged byxe2x80x94roadway protrusions, such as manhole covers or bridge joints, and, consequently, must be operated at some distance above the level of the surface to be cleared. This practice leaves residual snow on the surface. This means that systems that use augers or cutters can be used only in conjunction with other snow removal means, physical or chemical, if the snow is to be completely removed.
Snow blowers do exist that use brushes rather than rigid augers. E.g., Klauer (U.S. Pat. No. 2,941,223; 1960) teaches a manually operated system that uses two spiral brushes, oppositely wound around a rotating shaft, to transport snow to the center of the shaft. Alternatively, Maisonneuve et al. (U.S. Pat. No. 3,886,675; 1975) teaches the combined use of a rotating brush and an auger to engage snow and transport it to the blower unit. Rotating brushes, unlike rotating cutters and augers, can be operated in direct contact with the ground surface. Brushes, however, have a disadvantage in that the bristles in the brushes are round and, thus, only the snow particles that hit the leading edge of the bristles are propelled forward. All others are deflected laterally to varying degrees. Brushes also require a great deal of power to engage and lift the snow. This is because, typically, every bristle contacts the ground and, thus, every bristle bends, its tip contacting the ground. This results in the leading edge of the bristle actually facing downward before the bristle tip starts its desired forward and then upward movement as the tip loses contact with the surface. As a result, the snow is initially driven downward before it is propelled upward and forward. This results in a packing of the snow, making it more resistant to being passed through the rest of the device. Furthermore, since all the bristles drag on the ground, they encounter a frictional force that works against the direction of the brush rotation. This increases the power demanded to maintain that rotation at an effective rate.
As described above, snowblowers with brushes, augers or rotary cutters typically transport the snow to a centrally situated blower unit for expulsion. This means that the snow is handled for an extended period of time, as it travels from the outer edge of the snow collection means to the center, or, when dual snowblowers are used, as it travels from the center of snow collection device to the outer edges. The longer the snow remains in the system, the greater the volume of snow that is being handled or transported at any given time. Thus, snowblower systems must be designed to accommodate these large volumes and provided with the power required to move them. Also, the fact that snowblowers pack the snow as it is handled means that more power is required to transport the snow then would be the case with loose fluffy snow. Furthermore, the high-density, packed snow often causes the equipment to jam, leading to interruptions and potentially hazardous operations to clear the device.
Snow or debris removal systems are generally dedicated systems, i.e., a snow removal system is designed to remove only snow; a street sweeper is designed to remove only dirt and loose debris from the ground. As a consequence, cities, towns, and other entities that must be concerned with removing snow or debris from ground surfaces are required to invest in multiple costly devices to perform various necessary ground cleaning operations. It would be of great advantage if a system for removing snow and other debris could be rapidly and easily reconfigured as required to perform various ground surface cleaning operations, such as removal of frozen slush or fallen leaves or other loose debris, in addition to snow removal.
Therefore, what is needed is a snow removal device that will cleanly and safely remove snow from ground surfaces and discharge the snow without creating snowbanks that narrow the roadway or impair visibility. What is further needed is such a device that will fracture the snow into small, light units, thereby improving the operating speed, efficiency, and safety of such a device. What is yet further needed is such a device that will cleanly remove snow from irregular ground surfaces. What is still further needed is such a device that can be rapidly and easily reconfigured to perform various ground surface cleaning operations.
It is an object of the present invention to provide a snow removal device that will cleanly and safely remove snow from ground surfaces and discharge the snow without creating snowbanks that narrow the roadway or impair visibility. It is a further object of the invention to provide such a device that will fracture the snow into small, light units. It is yet further an object of the invention to provide such a device that will remove snow from irregular ground surfaces. It is still further an object of the invention to provide a device that can be rapidly and easily reconfigured to perform various ground surface cleaning operations.
The apparatus of the present invention provides a novel means for cleanly and efficiently removing snow and other debris from ground surfaces, regardless of whether the surfaces are level. The equipment is safer to operate than either snowplows or auger-using snowblowers, it is easily accessible for cleaning and maintenance, and requires a minimal amount of operating energy. The basic units of the system of the present invention are a novel rotating pick-up assembly mounted in close proximity to an impeller assembly. The system can be contained on its own chassis and pushed in front of, or pulled behind, a prime mover such as a truck, or can be self-propelled, or mounted on another vehicle.
In its Preferred Embodiment, the removal system of the present invention is mounted on a floating chassis attached to and suspended from a xe2x80x9cfixedxe2x80x9d chassis that can be pulled or pushed. The fixed chassis is designed to support floating chassis of varying widths. The moving components of the system are powered by a hydraulic power unit, or other power means, that can be incorporated into the system, or provided externally. The basic units of the removal system are a pick-up assembly, an impeller assembly, and a discharge tube. The pick-up assembly consists of a drum array mounted on a drum shaft that runs parallel to the ground surface and perpendicular to the direction the system is intended to move. The drum array may be formed from a plurality of interconnected drums, or it may consist of an individual drum.
Most importantly, each drum carries an array of finger modules and each finger module includes an array of flat fingers, each of which is an elongated, thin element. Fingers offer distinct advantages over snow removal equipment that uses plow blades, augers, cutters, or rotary brushes. Made of a stiff, yet flexible material, they will flex when they come into contact with fixed protrusions on the surface, unlike rigid plow blades, augers or cutters. As a result, the fingers are much less likely to be damaged by objects on road surfaces; also, they will not damage protrusions on the ground surfaces such as manhole covers and bridge joints. This finger module is the heart of the present invention, which thereby provides advantages over rigid, straight-edged plow blades, rotary brushes and augers and cutters with respect to its ability to sweep surfaces clean of debris, including snow.
In the Preferred Embodiment, these stepped finger modules have three fingers: a leading finger, a middle finger, and a trailing finger, each successively longer. In the operating position, the distance of the pick-up assembly from the ground is adjusted so that the middle finger just grazes the mean level of the ground surface. With the drum rotating in a direction that causes the snow to be flicked forward to the impeller openings, the leading finger does not touch the road surface at all, but rather strikes the snow at some short distance above the ground. As this leading finger hits the snow, it fractures it, i.e., it breaks the snow into small particles, and, as the finger continues through into its forward and upward rotation, it lifts the snow particles into the vicinity of the impeller assembly intake. With the apparatus operating in this manner, the middle finger just grazes the ground surface and conveys forward and upward the snow that the leading finger left behind. The trailing finger, having a length greater than the distance needed to reach the ground, flexes and drags when it contacts a flat surface. Thus, it is able to scoop snow out of depressions in the road or ground surface. In short, the leading finger fractures and displaces the snow down to within an inch or so above the ground. Because it is just moving through snow, without scraping against the road surface, this lead finger encounters minimal xe2x80x9cback forcesxe2x80x9d and, consequently, presents minimal drag on the drum rotation. The middle finger fractures and lifts the snow left by the leading finger, also transmitting little back force to the drum, since it just grazes the surface and does not have to flex and drag on the ground. The trailing finger, when it contacts the ground, does flex and scrape the ground, thus creating a back force on the drum. However, since it is not lifting any significant amount of snow (the bulk of the snow having already been cleared away by the leading and middle fingers), the ground resistance is about all that contributes to its drag. Thus, in contrast to snowblower systems or plows that compact the snow in the pick-up process, the pick-up assembly of the present invention breaks the snow into small units while it lifts it from the surface, cleanly and with a minimal force on the drum. The fingers offer a further advantage in that individual fingers can easily be replaced when they eventually become worn or damaged, in contrast to the large snowplow, auger, or brush assemblies, each of which can be very costly to replace.
The snow removal device of the present invention is intended to be used in connection with new snowfall as well as with packed snow. In normal operating mode, the lower half of the drum is rotating in the direction of travel of the system, with the shorter finger being the leading finger. For light fluffy snow, the direction of the rotation of the drum can easily be reversed, so that the lower half of the drum is rotating opposite the direction of travel. In this mode of operation, the longer finger becomes the leading finger, with the middle and shorter fingers providing a stiffening and strengthening of the leading finger. The snow is swept backward and upward, propelled around the drum, and driven from above into the impeller assembly. The advantages of operating the system in this reverse mode are twofold: the system can be operated at greater travel speeds, and less power is required to operate the drum.
The impeller assembly includes one or more impeller units. In the Preferred Embodiment, four impeller units are arranged in an array such that an axis that passes through the centers of them all is perpendicular to the direction of travel of the snow-removal apparatus and parallel to the pick-up assembly""s drum shaft. The impeller assembly is mounted on the floating chassis adjacent to the pick-up assembly. The impellers are similar to fans that move large volumes of air. In this case, the action of the impellers creates a pressure gradient such that all snow brought near the intakes is sucked into them. Each impeller unit includes an impeller blade array attached to an impeller shaft and to an impeller base plate, and an impeller chamber formed by an impeller chamber cover and impeller chamber walls. The impeller blades rotate in impeller chambers and, as an impeller blade approaches the opening between the chamber and the discharge tube, the rotational impeller action flings the snow into the discharge tube whence it is expelled from the system. The direction of impeller rotation is reversible, therefore the snow can be discharged to either side of the system, as desired. The discharge tube lies in the same plane and is parallel to the impellers and, thus, discharges the snow transversely at a relatively low height, using to advantage the fling momentum of the impellers and reducing the danger of snow cloud formation.
In normal operation, the plane of the impeller intake is tilted only slightly upward toward the pick-up assembly; however, the section of the floating chassis that supports the impeller/discharge assembly can be pivotally attached to the section of the floating chassis that supports the pick-up assembly so as to allow the plane of the impeller intake to be tilted at a steeper angle. Increasing the angle of the plane of the impeller assembly/discharge tube relative to the ground brings the impeller intake closer to the pick-up assembly, thereby decreasing the distance the snow must travel between the exit point of the pick-up assembly and the impeller assembly intake. This is advantageous when clearing wet snow. Increasing the tilt of the impeller intake plane also raises the height of the discharge tube, changing the height and angle of discharge, which may be desired in certain conditions. The use of multiple impellers has distinct advantages over systems that utilize only a single or two blower units. The pick-up assembly does not need to transport the snow as far to deliver it to the impeller unit because of the proximity of the impeller assembly intake to the pick-up system. Also, the xe2x80x9cnegativexe2x80x9d pressure that is created along the length of the pick-up assembly by the impeller action assists the delivery process by sucking the snow into the impellers. Furthermore, the snow is handled for a much shorter period of time before it is dumped into the discharge tube and, consequently, the use of multiple impellers reduces the volume of snow that is within the system at any one time. Thus, the impeller assembly handles the snow more efficiently and can be much more compact in design relative to other known snowblower systems of equivalent capacity.
Separate housings enclose the pick-up assembly and the impeller assembly/discharge tube so that during operation all sides, with the exception of the bottom of the pick-up assembly, are enclosed. This enhances the operating safety of the system because no moving parts of the apparatus are exposed during operation. Removable access covers can be opened to provide access to the pick-up assembly and the impeller assembly and discharge tube from above, making the assemblies readily accessible for cleaning and maintenance.
The apparatus of the present invention has three operating positions: an idle position in which the fingers of the pick-up assembly only reach to within one or two inches of ground level; a working position in which the middle finger just grazes the ground; and a transport position in which the entire device is raised and supported so that the fingers only come to within six to eight inches of the ground. For cleaning and maintenance operations, the floating part of the apparatus can be raised still further above ground level or the fixed chassis can be lifted from above to provide easy access to the pick-up assembly and the impeller assembly and discharge tube.
The device of the present invention is a versatile system that can be used for purposes other than snow removal. For example, the pick-up assembly with the finger modules can also be used for cleaning streets of debris in the summer. Furthermore, the drum with the finger modules can be easily and conveniently removed and replaced with another drum, such as a drum fitted with special blades or chains for removing ice, or with a brush for removing sand from the road in the spring. Furthermore, the versatility of the system is enhanced by the fact that the fixed chassis of the system can support varying widths of a floating chassis and the fact that the drum can rotate in a forward or reverse direction relative to the direction of translational travel.
The drum array according to the invention, is also, by itself, a device that can be used for many different ground surface cleaning operations. For example, the drum array with the blade-like fingers can be mounted in a conventional airport or runway broom and be used to clear runways of snow, sand, leaves, and other types of debris. Indeed, the drum array can be appropriately sized and mounted in any number of different power sweepers, such as, in relatively small, powered sweepers for home use or in large sweepers for municipal street-cleaning operations. The drum array can be front-mounted, rear-mounted, loader-mounted, or towed behind a vehicle.
In summary, the present invention includes a drum array with blade-like fingers that can be used with any number of powered ground-surface cleaning equipment, and a ground-surface cleaning apparatus that includes a pick-up assembly with the drum, an impeller assembly and a discharge tube. The pick-up assembly and the impeller assembly are both mounted on a floating chassis that in turn is mounted on a fixed pullable or pushable chassis. The drum of the pick-up assembly and the blades of the impeller assembly are driven by hydraulic motors mounted on the floating chassis. All moving parts of the system are enclosed in housings or under hoods during operation, greatly improving the safety of operating such a system. As the drum in the pick-up assembly rotates, the stepped, triple-finger modules fracture the snow and lift it into the vicinity of the impeller assembly, where it is sucked into the impellers and discharged to either side of the system through the discharge tube. The use of stepped fingers allows the snow to be broken up into small units, rather than be compacted, as is the case with snowplows and brush, auger, or cutter snowblowers. This offers several advantages: the snow is lighter and easier to transport, less power is required for its transportation, and the fracturing action of the fingers reduces the probability of the snow packing while being handled, thus increasing safety and efficiency. The use of flexible-yet-stiff fingers offers further advantages in that the fingers clean uneven road surfaces of snow efficiently and without damage to the snow removal equipment or to protrusions from the road surface such as manhole covers and bridge joints. The use of fingers is also cost effective, as the fingers can be replaced individually should they become worn or damaged. The use of multiple impellers provides a more efficient, compact design than the use of simply one or two impellers and also creates a suction force that aids in delivering the snow into the discharge assembly. Furthermore, the location of the discharge tube allows for relatively low transverse discharge, thus reducing the formation of snow cloud and improving visibility for other vehicles and pedestrians in the vicinity of the operating system. A device for removing snow or other debris from ground surfaces which has several different, easily and rapidly interchangeable drums, each configured to perform a certain ground cleaning operation, offers cost-saving advantages to entities that must acquire several different devices to perform the various typical cleaning operations on roads and other ground surfaces.